Inthewilderness the thing about ABA is that it is simply a method of teaching children/people how to cope and how to learn new skills. If my ds really would enjoy something and really wants to join in but struggles with one aspect of it (eg team rules in football, or having to run within lines on a race track for example), I would do everything I could to help him learn those skills.
I also know that since we started ABA and started equipping ds with skills in areas he was finding difficult, I have not left any activity in tears (a frequent occurence in his early years), and more importantly, he has become 100x happier in every aspect of his life. When he was 3yo he didn't know how to communicate, how to interact, how to play. Within six months of ABA he had been given a way of communicating, learning how to interact, and how to play.
Sorry, I really don't mean to pick you out personally, but I do feel saddened when people are told to lower their expectations.
You wouldn't think of an nt child "oh reading is hard for them - let's lower our expectations and not try and teach them". Imo there's no reason why you should not try and do the same with children with ASD - obviously you would differentiate according to their development/abilities etc but just to give up on even trying to teach a child (whether through ABA or any other intervention) is damaging.
Rant over, sorry.
I hope this hasn't come across as personal, don't mean it to - I just feel really strongly about this.
FWIW I also agree that a teenager could do the same job in this particular circumstance - but could easily be trained in simple techniques to help the OP's ds in learning the rules of the club.